BEAM ELEMENT STRUCTURAL DYNAMICS MODIFICATION USING EXPERIMENTAL MODAL ROTATIONAL DATA

Structural dynamic modification (SDM) of a fixed-free (cantilever) bea m to convert it into a fixed-fixed beam with experimental modal data i s presented. The SDM focuses on incorporating experimental rotational degrees-of-freedom (DOF) measured with a novel laser measurement techn ique. A cantilever beam is tested to develop the experimental modal da tabase including rotational degrees of freedom. A modal database from a finite-element model also is developed for comparison. A structural dynamic modification, with both databases, is performed using a Bernou lli-Euler beam to ground the free end of the cantilever beam. The hard ware is then modified and a second experimental modal analysis of the resulting fixed-fixed beam performed. A finite-element model of the fi xed-fixed beam also was created. Comparison of results from these four tests are used to assess the effectiveness of SDM using experimental modal rotational data. The evaluation shows that provided high quality experimental rotational modal data can be acquired, SDM work with bea m elements can be effective in yielding accurate results.